Now that BlackBerry has fallen significantly behind Apple and Google in the race to offer features and third-party apps for its smartphones, the company is concentrating on providing devices that, it claims, have the strongest available security -- its "killer feature" for enterprises that have exceptional security needs. At a company-sponsored symposium in New York today, BlackBerry executives made the case that the company's devices and services could offer levels of security for enterprises mobile devices that can not be replicated on Apple, Android, or other mobile devices.